Space images propel Cape Town's urban forest dream towards reality

In its quest to become an “urban forest”, Cape Town says it is the first SA city to map its trees.

With tree coverage of 7%, the city falls short of the UN Food and Agriculture Organisation definition of an urban forest, “a contiguous area with over 10% tree canopy cover”, said mayoral committee member for community services Zahid Badroodien.

“Mapping our trees will further assist us in decision-making on where to focus tree-planting efforts, especially if overlaid with heat island maps,” said Badroodien.

“Implementing techniques such as selection, planting, training, fertilisation, pest control and pruning are important in caring for our trees. Trees play an important interface role between the environment and the urban landscape.”  

In June last year, the city recreation and parks department began analysing an infrared satellite image which allowed it to distinguish tree canopies by their colour.

Using light detection and ranging data (LiDAR), which provided height information, the department was able to include only trees taller than 2.75m.

Badroodien said an important component of managing the urban forest is a tree inventory.

“The data record for a tree typically includes information about tree species, location, characteristics, images, maintenance history, risk assessment and further maintenance and management needs,” he said.

“The value of trees cannot be overestimated. While they assist in providing cleaner air, they also offer environmental protection against erosion and act as noise buffers.”